Hello All:

I am working with a Government Client to perform an Arc Flash Hazard Risk Evaluation. For this project they provided a design guide with a few requirements they have for this study. I was curious if anyone has recognized similar requirement and perhaps a suggestion on where/how they came up these. I would like to review these references and determine if these are items I should be considering for every evaulation project.


#1) Run a seperate scenario for each utility primary side contribution:
a) Max of 10,000A
b) Min of 3,000A

Does IEEE or other publication suggest to do something like this?

#2) When under generator power assume that N-1 motors are in service.

Any idea why N-1 and not all motors. (I am also assuming they are referring N-1 motors of the same function and HP)

#3) The following assumption shall be made for plotting raw sewage pumps on TCC and sizing motor circuit prtective devices (for a lift station):
a) FVNR Istart=FLA x NEMA Code Letter Mulitplier
b) VFD Istart=2.5xFLA
c) SSRV Istart=3.5xFLA

Is there a standard publication that gives these suggestions?

#4) Run utility and generator scenarios with each of the following sewage pumps subtransient reactance (Xd")
a)Xd"=0.167 (NEMA Code "G" - Xd"=FLA/LRA=0.167)
b) Xd"=0.167x3=0.5

Again, is there a standard publication which suggests doing so with these motor values?